<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<style>
    body {
        margin: 0;
        padding: 0;
    }

    #container {
        background: red;
        /*width: 10vw;*/
        /*height: 10vh; */
        /*width: 10vmax;*/
        /*height: 10vmax;*/
        width: 10vmin;
        height: 10vmin;
    }
</style>
<body>
<p>vw&&vh</p>
<div id="container"></div>
</body>
</html>